The present invention relates to mixed-metal carbonyl cluster compounds and more particularly to improved synthesis routes for their preparation and to novel mixed-metal carbonyl cluster compounds.
H.sub.2 FeOs.sub.3 (CO).sub.13 was first isolated by Moss and Graham, J. Organomet. Chem. 23, C23-C24 (1970), as a by-product in 6% yield from the reaction between H.sub.2 Os(CO).sub.9 and Fe.sub.2 (CO).sub.9. Subsequently, Geoffroy and Gladfelter, J. Am. Chem. Soc., 99, 7565-7573 (1977), found that the reaction between the electron precise cluster Os.sub.3 (CO).sub.12 and Fe(CO).sub.4.sup.2- followed by protonation gave H.sub.2 FeOs.sub.3 (CO).sub.13 in 9% yield.
Other tri-osmium chemistry can involve the addition of nucleophilic organometallic reagents to the electronically unsaturated hydrido-osmium carbonyl cluster H.sub.2 Os.sub.3 (CO).sub.10 as a pathway to larger transition metal clusters. Such addition exploits the Lewis acid character of the tri-osmium system as exemplified by Stone and co-workers finding that certain electron rich d.sup.8 and d.sup.10 metal complexes will add to H.sub.2 Os.sub.3 (CO).sub.10 to yield a number of new heteronuclear transition metal clusters. Farrugia et al., J. Chem. Soc. Chem. Comm., 260 (1978). For further studies on H.sub.2 Os.sub.3 (CO).sub.10, reference is made to the following: Keester et al., JACS, 98:4, 1056-1057 (1976); Deeming et al., J. Organometal Chem., 114, 313-324 (1976); and Ferrari et al., Inorganica Chemicta Acta, 20, 141-143 (1976).
We have now discovered that, besides the previously-mentioned Lewis acid character, H.sub.2 Os.sub.3 (CO).sub.10 also possesses apparent Lewis base character and that this Lewis base character of H.sub.2 Os.sub.3 (CO).sub.10 may be used to provide new heteronuclear bimetallic cluster compounds and new pathways for the high yield synthesis of H.sub.2 FeOs.sub.3 (CO).sub.13, and other known heteronuclear bimetallic cluster compounds.